1. Field of the Invention
The present invention relates to a tap changer, and particularly to a tap changer changing a tap of a connected transformer during no load condition.
2. Description of the Background Art
Japanese Patent Laying-Open No. 2007-258393 is provided as a prior art document disclosing a tap changer for a load condition that allows reduction of eddy current loss occurring in a lead-through portion of a drive mechanism to alleviate current limitation due to the eddy current loss.
In the tap changer for a load condition disclosed in Japanese Patent Laying-Open No. 2007-258393, a connection lead between a changeover switch and a tap selector is formed of a connection lead on the odd-number side and a connection lead on the even-number side.
The connection lead on the odd-number side is formed of an upper drawn lead that is drawn from an annular contact on the odd-number side to extend upward and connected to the terminal on the odd-number side of the changeover switch; and a lower drawn connection lead that is drawn from an annular contact on the odd-number side to extend downward and connected to the terminal on the odd-number side of the changeover switch. The connection lead on the even-number side is formed of an upper drawn connection lead that is drawn to extend upward and a lower drawn connection lead that is drawn to extend downward.
By forming the connection leads on the odd-number side and the even-number side from two parallel leads including an upper drawn lead and a lower drawn lead, the current flowing through each of the upper and lower drive mechanisms can be reduced to half of the current in the case of the conventional technique, to suppress heat generation caused by eddy current loss.
By the eddy current generated within the tap changer, contact portions of the tap changer may be locally overheated.